The proliferation of Online Social Networks (OSNs) has enabled users to interact with others of similar interest over a network, e.g., the Internet. It is not unusual that a user may visit OSN and non-OSN websites. However, the user's browser may be asked to visit an aggregator. An aggregator is a third-party Web server that tracks user activity across various (OSN and non-OSN) first-party sites to create a behavioral profile. During that visit to an aggregator, information about the user is handed to the aggregator along with the aggregator's tracking cookie. The same tracking cookie is also sent to the aggregator when the user visited (or will visit) the non-OSN website. Thus, the aggregator is able to link the information that it received from the OSN site due to leakage of user's personal information with the tracking cookie already in its possession. Such linkage enables the aggregator to identify the user who visited the non-OSN site. Therefore, the aggregator will be able to determine the identity of the user who visited the non-OSN site as well as OSN site.